1. Field of the Invention
The present invention relates to a structure for connecting eyeglass parts, in particular those eyeglass parts which constitute a metal eyeglass frame.
2. Description of Prior Art
There have been used stainless steels, nickel-chromium alloys, German silver, phosphor bronze or other metallic materials, as the parts constituting the metal frames of eyeglass. Recently, pure titanium or some nickel-titanium base alloys (i.e., Ni-Ti alloys) also have been made use of as said eyeglass parts because they are excellent in their properties such as mechanical strength, corrosion resistance, spring property or resilience and are lighter in their weight. In particular, Ni-Ti alloys are very useful in this field owing to their excellent characteristics including super elasticity which enhances to them the so-called "shape memory" property depending upon their compositions.
It is however difficult to solder the parts of pure titanium or the Ni-Ti alloys to each other or to other materials. Said metal or alloys should thus be coated with a nickel plating membrane or other plating before they are soldered to the other eyeglass parts made of German silver or other readily solderable materials, the plating membrane thereby being interposed for instance between Ni-Ti alloy phase and German silver phase.
Such interpositon of the plating membrane between the surfaces of soldered materials brings about insufficient junction strength. It is also disadvantageous to add such plating step to the process for manufacturing the eyeglasses.